If you install this and all text turns red, then things are working.
// ==UserScript==
// @name Greasemonkey/Tampermonkey/Violentmonkey test style
// @namespace http://userstyles.org
// @description If you install this and all text turns red, then things are working.
// @author JasonBarnabe
// @homepage http://gf.zukizuki.org/scripts/1
// @run-at document-start
// @version 20231121.2
// @include *
// ==/UserScript==
(function() {
var css = "*{ color: #F00 !important; }";
if (typeof GM_addStyle != "undefined") {
GM_addStyle(css);
} else if (typeof PRO_addStyle != "undefined") {
PRO_addStyle(css);
} else if (typeof addStyle != "undefined") {
addStyle(css);
} else {
var node = document.createElement("style");
node.type = "text/css";
node.appendChild(document.createTextNode(css));
var heads = document.getElementsByTagName("head");
if (heads.length > 0) {
heads[0].appendChild(node);
} else {
// no head yet, stick it whereever
document.documentElement.appendChild(node);
}
}
})();